Spiny Norman said:

No, less than that. The 60% uranium would have to be refined to up around 90% or so. And from what I understand the modern implosion designs can use as little as 9 kg each. I may well be very wrong with that though.

Nah, you need at least 15kg of 90%, and you really do need a good beryllium reflector for that. And, it just might fizzle, leaving you with ‘dirty bomb’ effects

Yeah, if you take it to 90%, you get about25 kg of enriched uranium. That’d give you a bomb about equivalent to Hiroshima. I don’t know how it’d go if there was, say, a beryllium reflector in there.